Key words: organic farming, milk production, grazing system, annual swards, perennial swards, pasture species, compost fertilisation

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2 Kuusela, Eeva Grazing management for Nordic organic dairy farming University of Joensuu, 2004, 154 pp. University of Joensuu, PhD Dissertations in Biology, No. 32, ISSN ISBN Key words: organic farming, milk production, grazing system, annual swards, perennial swards, pasture species, compost fertilisation Grazing dairy cows form part of a complex ecosystem involving their interaction with the pasture plants, soil micro-organisms and climatic conditions. In Nordic organic dairy farming, grazing represents a challenge with the short grazing season and limited number of winter-hardy plant species combined with restrictions on the use of fertilisers and supplementary feeding. The aims of this study were to investigate factors limiting grazing and to develop adjusted grazing management for Nordic organic dairy farming conditions. The study, including seven field or feeding experiments, was conducted on the Siikasalmi experimental farm of the University of Joensuu (62 30 N, E) in Eastern Finland in The focus in the study was to combine the aspects of plant, animal and organic production, as they are all involved in organic dairy pastures. This pioneer work provides a characterisation of Nordic organic pastures, suggests novel legume species for Nordic conditions, considers the use of manure compost fertilisation, proposes tools to improve grazing efficiency and assesses the benefits of supplementary feeding. This study showed that intensively managed organic pastures can support at least moderate herbage production with good nutritive value, although organic pastures are heterogeneous mixtures of three botanical components, grasses, legumes and weeds, which are clearly divergent regarding dependence on soil nitrogen availability and herbage nutritive value. The botanical proportions and seasonal changes affect the nutritive value and growth of the herbage. The choice of legume species for grazed mixture is of key importance. White clover is the most suitable perennial pasture clover for Nordic conditions, but the additional inclusion of beneficial birdsfoot trefoil in perennial clover-grass mixtures is suggested. Hairy vetch is best suited for grazed annual legume-grass-cereal mixtures and can support extended grazing in the autumn. At the farm level, including both annual and perennial swards will help to balance the temporal variation of the herbage mass and extend the grazing season in the autumn. Application of soil-deposited manure compost increased herbage production, but decreased proportion of utilised herbage and had no effect on the amount of utilised herbage. Hence, manure compost fertilisation, if necessary to improve the soil fertility of a certain area, is recommended to be used for cereals included in pasture-crop rotation rather than for grazed swards. It should be noted that in organic farming systems herbage production is often lower than in heavily fertilised conventional systems when normal rotation cycles are used in order to obtain herbage with adequate nutritive value. The pre-grazing herbage mass affects the stocking rate, grazing area requirement, milk yield per animal and milk yield per hectare. The milk yield per hectare was clearly increased by applying daily strip grazing instead of paddock grazing. In organic dairy farming, excessive herbage allowances are rarely useful because of the limited pregrazing herbage mass. The herbage allowance should not go below the level which the system can tolerate. Post-grazing sward height is a good indicator for the implementation of adequate allowances and for continuous monitoring to prevent inefficient under-grazing and detrimental over-grazing. In the present study the milk-yield response to concentrate feeding was relatively high ( kg milk per 1 kg concentrates). Both energy and protein supplementation resulted in increased milk production. The organic pasture herbage did not fully satisfy the mineral requirements of grazing dairy cows. Low concentrations of Na and Mg in herbage, especially the latter associated with high K, require mineral supplementation. Eeva Kuusela, Department of Biology, University of Joensuu, P.O.Box 111, FIN Joensuu, Finland 3

3 ABBREVIATIONS ADF DM CP GP HA HM IVOMD NDF PRE HM POST HM POST SH S grazing P grazing acid detergent fibre dry matter crude protein grazing period, animal occupation period on grazing area within a rotational grazing system herbage allowance herbage mass in vitro organic matter digestibility neutral detergent fibre pre-grazing herbage mass post-grazing herbage mass post-grazing sward height Strip grazing Paddock grazing 4

4 CONTENTS page LIST OF ORIGINAL PUBLICATIONS INTRODUCTION What is organic farming? Development of organic farming in Finland Background of Finnish grazing concept Grazing - an essential part of organic dairy systems THE PRESENT SITUATION Grazed species Plant nutrition and fertilisation Implementation of grazing Animal nutrition and supplementary feeding Actual problems on farms AIMS OF THE STUDY MATERIAL AND METHODS Site of the experiments Experimental design and treatments Implementation of the experiments RESULTS AND DISCUSSION Characterisation of organic pastures Novel legume species for grazed mixtures in Nordic conditions Use of manure compost fertilisation Improvement of grazing efficiency Need for supplementary feeding Evaluation of methods used CONCLUSIONS ACKNOWLEDGEMENTS REFERENCES

5 LIST OF ORIGINAL PUBLICATIONS This thesis is mainly based on the following publications but it also includes some previously unpublished results. In the text the publications are referred to by the Roman numerals I-V. I II Kuusela, E., Khalili, H Effect of grazing method and herbage allowance on the grazing efficiency of milk production in organic farming. Animal Feed Science and Technology 98, Khalili, H., Kuusela, E., Suvitie M., Huhtanen P Effect of protein and energy supplements on milk production in organic farming. Animal Feed Science and Technology 98, III Kuusela, E., Khalili, H., Nykänen-Kurki, P Fertilisation, seed mixtures and supplementary feeding for annual legume-grass-cereal pastures in organic milk production systems. Livestock Production Science Vol 85/2-3, IV Kuusela, E. Annual and seasonal changes in production and composition of grazed clover-grass mixtures in organic farming. Agricultural and Food Science 13, V Kuusela, E. Annual and seasonal changes in mineral contents (Ca, Mg, P, K and Na) of grazed clover-grass mixtures in organic farming (submitted manuscript, Agricultural and Food Science). Publications I-IV are reprinted with permission from publishers. Copyright for publications I-III by Elsevier Science and for IV by The Scientific Agricultural Society of Finland. 6

6 1 INTRODUCTION 1.1 What is organic farming? The main aspects of conventional farming against which have been criticised are the increased use of chemicals: mineral fertilisers, herbicides, pesticides and fungicides in crop production and feed additives, hormones and antibiotics in animal production (Sundrum 2001). Therefore organic farming has been developed as an alternative. Organic farming aims to minimise the use of external inputs and represents a deliberate attempt to make the best use of local natural resources. According International Federation of Organic Agriculture Movements (IFOAM) organic agriculture comprises a whole system approach based upon a set of processes aiming to support a sustainable ecosystem, safe food, good nutrition, animal welfare and social justice (IFOAM 2002). Since 1980, the IFOAM has created international standards for what may be labelled as organic. Within the European Union, Austria and the Scandinavian countries are in the forefront in the proportion of their agricultural area devoted to organic farming, and Denmark in the share of organic dairy farming in its agriculture (Sehested et al. 2003). The first Finnish standards for plant production and animal production were developed by Luomuliitto ry (the Union for Organic Farming) in 1986 and 1988, respectively (Heinonen 2002). Today in all the EU countries regulation 1804/1999, supplementing regulation 2092/91 on organic production, provides a minimum standard concerning the right to label food as organic (CEC 1999). In Finland, the state authorities carry out the inspection and certification of organic production. Ministry of Agriculture and Forestry Decrees No 346/2000 and No 127/2001 specify the authorities and the inspection and control system for organic production (KTTK 2003). 1.2 Development of organic farming in Finland Although the first traces of the ideas of organic agriculture in Finland as Natural Agriculture and Biodynamic Farming date back to the beginning of the 20th century, the biochemist Professor A.I. Virtanen can be considered the pioneer of organic farming in Finland (Heinonen 2002). During the 1930s, Virtanen developed a nitrogen self-sufficient cultivation method, which included crop rotation with pastures, bread grains and intensive red clover leys for winter feeding preserved as silage. The AIV method was first developed for preserving the valuable clover herbage (Virtanen 1938). The oldest existing organic farms in Finland were converted in the 1960s, but until the 1980s there were less than thirty organic farms (Heinonen 2002). These pioneers, although many of them were economically as successful as conventional farmers, had ideological motivations for converting. During the 1980s, specialised marketing channels started to function and in 1990 the state conversion aid programme was launched. In 1989 there were 373 certified organic farms, but mainly due to the conversion aid, the number of farms started to increase. Finland s entry into the European Union at the beginning of 1995 brought more farms to convert to organic farming. In Finland the number of organic farms in 2003 was 4983 (6.8% of all farms) and the area under organic cultivation or being converted was hectares (7.2 % of total area) (KTTK 2004). Converting animal production to organic farming 7

7 is not a requirement for conversion or for receipt of production aid for organic farming. About 45% of Finnish organic farms practise animal production, but in 2003 only 413 farms had certified organic animal production and 218 farms had organic milk production (KTTK 2004). The strategy of the Ministry of Agriculture and Forestry aims at reaching a 15% share of organically farmed land in Finland by 2010 (KTTK 2003). The action plan for emphasizes the development of organic animal production. Future environmental and food trade policies within the European Union, and also worldwide, may further increase interest in local low-input systems in peripheral regions. The political environment within which livestock farming in much of Europe operates (Common Agricultural Policy) is shifting the balance of economic advantage towards legumes and away from high usage of inorganic fertilizer (Rochon et al. 2004). However, in many parts of Europe there has been a net decline in the use of forage legumes since the 1980s, despite the reputed value of legumes for low-input livestock production systems. Organic livestock farming often makes severe demands on farm management. The preference for home-grown feed and limitations in the choice of boughtin feed is bound to result in a wider and unintended variation in the nutritional value of animal diets under organic than conventional practices (Sundrum 2001, Hovi et al. 2003). Consequently, optimising the balance between the supply and requirements of nutrients is probably more challenging under organic than in conventional systems, especially if the quality of basal forages is low. From the farmer s standpoint, conversion of animal production systems increases production costs, effort and bureaucracy due to the housing, husbandry and feeding directions for organic animals (Koikkalainen and Haataja 2000). Also the underdeveloped market for organic animal products in Finland has retarded conversion. Compared to a few years ago, the market demand for organic milk products has recently been increasing relatively slowly. However, in practice all cows on organic farms, labelled or not, are mainly fed on farmgrown feeds (silage, pasture, cereals) of organic origin. The willingness of consumers to pay premium prices for alternative practices enables farmers to reduce economic pressure on production costs and to begin practising organic animal husbandry (Sundrum 2001). For organic milk the extra price in Finland is today about 0.06 euro per litre for contract producers, but at the moment new contracts are not being made and the future price support is uncertain. Because of market-led development of the situation of organic farming, organic animal husbandry especially depends to a high degree on consumers demand for organically produced products and for added values such as biodiversity, the preservation of species and the protection of nature, the landscape, groundwater or animals, etc., which are closely related to the production process (Sundrum 2001). In accordance with expectations, organic farming has been proven to increase the biodiversity in fields, field margins and other agricultural surroundings (Rydberg and Milberg 2000, Hopkins and Hrabe 2001, Pitkänen and Tiainen 2001) and to decrease the negative environmental impact of farming (Sundrum 2001, De Boer 2003). This is because organic farming does not use mineral fertilisers or pesticides, and its crop rotation cycle is considerably more varied than in modern conventional farming, especially compared with monoculture cultivation of cereals. Also on dairy farms uneven and selective grazing can 8

8 be beneficial for biodiversity (Bailey et al. 1998). However, organic dairy farming may not be able to satisfy all the demands of consumers, where they are based on unrealistic ideas rather than on the biological facts of the production process. It should be pointed out that in Finland the average annual milk yield of recorded cows increased from 3275 kg in 1950 to 8121 kg in 2003 and will increase further (Finnish Milk Recording). The average annual milk yield of Finnish organic farms was 7193 kg in 2003 and on some organic farms, annual milk yields already exceed 9000 kg per cow. In Denmark, 6% of organic dairy farms have more than 9000 kg milk per cow (Sehested et al. 2003). It has sometimes been suggested that there should be separate breeding programmes for organic animal production aimed at sustainability and health rather than future increases in productivity. The greater the gap between conventional and organic milk yields, the greater is the need for financial support. In any case the nutritional requirements of current dairy cows with high genetic potential must be satisfied to support their welfare (Hovi et al. 2003). 1.3 Background of Finnish grazing concept In Finland, modernisation was initiated after the great famine years in the 1860s. More attention was paid to animal husbandry and particularly to dairy cows and, consequently, to grassland farming instead of low-yielding natural pastures. In the 1880s, two thirds of Finland s permanent agricultural lands were meadows, and only one third tilled fields (Pitkänen and Tiainen 2001). Grazing was based on meadows and forest pastures, which comprised a large diversity of species. It has been estimated that 30-40% of Finland s plants benefit from traditional forms of land use such as grazing and mowing (Alanen 1996). Today the remaining meadows and forest pastures are heritage landscapes, habitats that will not survive without specific preservation measures (Vainio et al. 2001). Since the 1960s, the best yielding intensively managed and rotationally grazed short-term pastures have generally been used in Finland. Only 0.03 of the Finnish forage production area comprises swards older than 4 years (Information Centre of the Ministry of Agriculture 1998). Hard winter conditions limit the number of potential grass species to only few such as timothy (Pleum pratence) and meadow fescue (Festuca pratensis), and in Southern Finland, cocksfoot (Dactylis glomerata) (Nissinen and Hakkola 1995). Before the increased use of N fertilisers, red clover (Trifolium pratense) was often included in seed mixtures (Heikinheimo 1948). Timothy, meadow fescue and red clover are climatically the best suited species for Finnish swards and organic pastures, although they are less tolerant of grazing than perennial ryegrass (Lolium perenne) or white clover (Trifolium repens), which are commonly used in Central Europe (Virkajärvi and Höglind 1999). In recent dissertation it was concluded that conventional timothy-meadow fescue pastures are tall, have low tiller population density, low herbage mass bulk density, occasionally low leaf content and similar nutritional value compared with perennial ryegrass pastures despite the structural differences (Virkajärvi 2004). Also smooth meadow-grass (Poa pratensis), red fescue (Festuca rubra) or recently tall fescue (Festuca arundinaceae) (Niemeläinen et al. 2001) has been recommended in some instances for Finnish grazed swards. 9

9 1.4 Grazing - an essential part of organic dairy systems Grazing dairy cows form part of a complex ecosystem involving their interaction with the plants of the pasture, the soil micro-organisms and the climatic conditions (Leaver 1985). Grazing is the most natural feeding method for cattle and also the cheapest source of nutrient for dairy cows thus contributing to the competitiveness of milk production, preserving the rural landscape and giving a beneficial image of dairy production. Grazing provides animal freedom for a wide range of species-specific behaviour and is also a natural source of vitamin D, but extreme conditions such as heat (>25 C) or wet combined with cold can stress grazing animals (O Connell et al. 1989, Hemsworth et al. 1995). According to organic farming regulations, cattle should have daily access to pasture when conditions are adequate for grazing (CEC 1999). In the Nordic Countries, milk production based on grazed grass is limited due to the short grazing season and in some cases as a result of low herbage yields from organic pastures. For example in Finland the length of the grazing season is 3-5 months. According to a farm study (16 farms), the yield of pasture decreased by 40% after converting to organic farming (Turkki and Viitala 1996). High yielding dairy cows are challenging grazing management in organic farming to exploit fully the potential contribution of herbage. In early-mid lactation, supplementary feeding is needed also at pasture to meet the demands of high-yielding animals. According to regulations, the proportion of forage (on a dry matter (DM) intake basis) must be at least 0.60, but during the first three months after calving the proportion of concentrates can be increased to a maximum of 0.50 (CEC 1999). According Finnish Milk Recording in 2002 the DM basis proportion of grazed herbage and hay in diet comprised about 0.13 and 0.04, respectively, both in organic and conventional milk production, but the proportion of silage in diet was higher for organic than for conventional milk production (0.44 and 0.39, respectively). 2 THE PRESENT SITUATION 2.1 Grazed species Due to climatic constraints, the grass species suitable for Nordic perennial organic legume-grass pastures are the same as those used in conventional farming. Although species may be the same, the herbage growth and quality of organically cultivated grasses may be different from conventional fertilised swards. Red clover has been used as the primary legume within Finnish organic farming systems owing to its high yield potential and relatively good winter hardiness, although it is not well suited to multiple-cut systems or close grazing (Nissinen and Hakkola 1995, Taylor and Quesenberry 1996, Clark and Kanneganti 1998). White clover tolerates frequent close grazing better and is the most important pasture legume in several regions of Europe (Frame and Newbould 1986, Schils et al. 1999). Some white clover cultivars recently introduced to Finland, for instance the Estonian Jögeva4, have proved to be reasonably resistant to frost (Nykänen-Kurki and Kivijärvi 1996, Sormunen-Cristian and Nykänen- Kurki 2000). Alsike clover has been recommended instead of red clover on acid and moist soils. It could be an alternative to red clover also in shortterm pastures. Applying a mixture of white and alsike clover might decrease 10

10 temporal changes in the proportion of clover because of the different growth rhythms of the species. In low-input grazing systems the beneficial effects of legumes on animal nutrition and soil fertility are well known, but so also is the risk of legume bloat, which is due to extensive ruminal fermentation which occurs following the ingestion of high quantity of legumes (Leaver 1985, Lane et al. 2000, Assefa and Ledin 2001, Beever et al. 1999). Only a few legumes such as birdsfoot trefoil (Lotus corniculatus) have been recorded as being non-bloating, whereas both clovers and vetches have been reported to cause bloat (Piper et al. 1923, Duke 1981, Min et al. 2003). The common recommendation not to graze on legume-predominated areas is difficult to follow in organic farming practice. According to Majak et al. (1995) legume bloat can be reduced by several ways: by advancing states of plant maturity, by moving cattle onto a new pasture in the afternoon, by grazing continuously and by applying bloat preventing feed supplements, which are not permitted in organic farming (CEC 1999). Majak et al. (1995) summarised, that grazing systems, which promote continuous and rapid ruminal clearance are most likely to reduce the occurrence of bloat. Birdsfoot trefoil contains condensed tannins which bind protein and hence prevent bloat and decrease rumen protein degradation (Tamminga and Suderkum 2000). Birdsfoot trefoil could be a useful legume for organic pasture farming. However, a more serious problem than high clover content in feeding is often the year by year decrease in the proportion of clover in Nordic perennial swards. Perennial pastures could be partly replaced by annual legume-grass-cereal mixtures. The different growth rhythms of perennial and annual pastures could balance the amount of herbage available during the grazing season and extend the season in autumn. In Finland, annual cereal-grass mixtures have already been introduced in conventional farming (Nissinen 1992, Nissinen and Hakkola 1998) and cereallegume mixtures for silage production in organic farming (Joki-Tokola et al. 2000). Common vetch (Vicia sativa), hairy vetch (Vicia villosa), Persian clover (Trifolium resupinatum) and some white clover varieties (Trifolium repens) could be suitable legumes for grazed annual mixtures under Nordic conditions (Duke 1981, Joki-Tokola et al. 2000). Clovers, like many other grazed legumes, are not dependent on N-fertilisation and are rich in CP and minerals, especially Ca and Mg, and low in neutral detergent fibre (NDF), cellulose and hemicellulose (Leaver 1985, Buxton 1996). Grasses have high contents of NDF, cellulose and hemicellulose, but their herbage production and herbage crude protein (CP) content is clearly dependent on soil N availability. Weeds, although unsown, comprise the third herbage component after grasses and legumes. Under conventional grassland management practices weeds are undesirable. For organic farming and other low-input systems they can have a beneficial role in improving biodiversity, the nutrient cycle and animal nutrition (Lampkin 1994, Wardle and Nicholson 1996, Kallah et al. 2000). Weeds can also be used as indicators of growing conditions. Dicotyledonous weeds are sometimes called forbs or herbs. 2.2 Plant nutrition and fertilisation In natural systems animal products can be seen as the result of a biogeochemical cycling of nutrients through soil, 11

11 water, air, plants, animals and manure (Tamminga 2003). In agroecosystems human intervention, such as external inputs of energy, fertilisers and feeds from distant areas, change the balance. The sustainability of livestock grazing has to meet the criterion of being an offtake of production (forage) without disruption to the functioning of the ecosystem (Vavra 1996). In organic farming, which aims to minimise the use of external inputs, herbage production is dependent on biological N 2 -fixation, soil mineralisation and nutrient recycling (Granstedt 1992, Lampkin 1994, Younie 1999). Well established pastures can maintain good soil fertility and support high herbage production since the majority of grazed nutrients are directly returned via the faeces and urinary excretion of the grazing animals (Holmes 1968, Leaver 1985). The establishment and maintenance of N 2 -fixing legumes in the sward should match the N losses from the pastoral system (Ledgard and Steele 1992, Weller and Cooper 2001). A high CP content of the herbage is indicative of substantial biological N fixation, partly capitalised in current herbage production and partly invested for future needs. Legume-poor unfertilised pastures have a uniform mosaic appearance with visible green patches of legume-rich areas, urination spots and zones around faeces. This is due to herbage N being removed from the whole pasture area but returned via faeces and urine to small areas at high concentrations (Wilkins and Garwood 1986, Afzal and Adams 1992). In organic pasture farming the need for other fertilisation, in addition to the recycled manure of the grazed animals, must be considered carefully. If urine is separated, diluted urine can be spread on the growing sward to promote grass growth similarly to mineral fertilisers. This system has been recommended also for those organic grazed swards with a decreased proportion of legumes. In 1994, the use of urine application was tested in a survey study at Siikasalmi (unpublished). Oneyear-old alsike, red and white clover grass plots (10 x 10 m) were divided into two similar areas (no replicates). Urine was applied (20 t ha -1 ) in early July. As a consequence the average pregrazing herbage mass (PRE HM) of the treated areas was increased (15%), postgrazing herbage mass (POST HM) was increased (25%) and clover proportion was decreased (23%) compared to the untreated areas. The application of urine affected both animal preference and sward composition. In August 1995, undesirably high herbage K contents (>40 g kg -1 DM) were recorded from a recently established sward which had received applications of diluted silage effluent and urine during the previous summer. Because of the risk of increased herbage K content and decreased animal preference, the effect of urine application was not studied further. However, for low K soils urine application might be useful (Baars 2002). The most commonly used fertiliser in organic dairy farming is manure. Each farm must consider individually how to make the best use of this important nutrient source. If animal production is based on farm-produced feeds, as recommended in organic farming, the amount of available manure per hectare is clearly limited because of the large area of forage needed per animal. On non-self-sufficient organic dairy farms almost all of the cultivated area is usually under perennial swards. In this case, replacing the manure accrued during the long indoor feeding period can be difficult, if it is not spread over the growing swards. On pastures, where urine and dung are directly recycled, the benefits of additional urine or manure 12

12 compost fertilisation could be lower than for other crops. Nevertheless, N fertilisation has positive linear effects on the HM production and CP content of grasses (Holmes 1968). However, manure fertilisation may reduce the legume proportion in mixtures and the smell of manure may decrease herbage utilisation during grazing (Marten and Donker 1966, Leaver 1985, Wilkins and Garwood 1986, Assefa and Ledin 2001). 2.3 Implementation of grazing Dairy cows performance is generally similar under continuous and rotational grazing systems (McMeekan 1956, Leaver 1985). The benefits of rotational grazing have usually been reported for legume-based swards at high stocking rates (Leaver 1985, Schlegel et al. 2000). Current plant species influence the choice of grazing system. For instance in Denmark continuous grazing is usually used with perennial ryegrass and white clover swards. Because winter-hardy grasses (timothy and meadow fescue) and also red clover suffer from close grazing, rotational grazing system is more suitable for Nordic organic dairy farming. Rotational grazing is also easier to manage than continuous grazing, because rotational grazing allows precise identification of grass quantity and quality (Campling 1975, Peyraud and Gonzalez-Rodrigez 2000). Strip (S) grazing is a more controlled form of rotational grazing and allows the vegetation to rest between grazings. In daily S grazing the specified quantity of grass per cow, i.e. daily herbage allowance (HA), is maintained by daily adjustment of the grazing area according to the HM. If the HA is too low, the milk yield per animal will decrease but excessive HA results in a lower milk yield per hectare. Post grazing sward height (POST SH) is a practical management tool for grazing. In conventional rotational grazing both intake and milk production depress if the cows are forced to graze the sward down to mean height less than 8-10 cm (Le Du et al. 1979). Hence low POST SH, indicative of over-grazing, will decrease the animal performance and also retard regrowth of the sward. High POST SH due to under-grazing will decrease the utilisation of pasture and consequently have a negative impact on herbage nutritive value, if swards are not topped. Targeting POST SH depends on the species, fertilisation, sward structure and grazing system (Le Du et al Parga et al. 2000). Both HA and sward structure affect the POST SH. For instance, daily HA of 12 kg DM (above 8 cm) and similar PRE HM ( kg OM ha -1 ) has been reported to result in lower POST SH for control sward compared to leafy sward (8.4 and 10.3 cm, respectively, Parga et al. 2000). In Finland, a POST SH of 10 cm is recommended, due to the low bulk density and relatively low tiller density of the prevalent grass species (Virkajärvi and Höglind, 1999, Virkajärvi 2004). This could be an adequate POST SH also for organic pastures in Finland, since the same grass species are used. 2.4 Animal nutrition and supplementary feeding Milk yield, which is the ultimate harvest from pasture, determines the needs of the animals. The nutritive value of the herbage and access to herbage affect the intake and nutrient supply in grazing cows (Leaver 1985, Mayne et al. 1999). For any given grazing system the pasture species, application of fertilisers, sward growing conditions, stage of maturity and stocking rate affect the nutritive value of the herbage (Leaver 1985, Delagarde 13

13 et al. 1997, Wales et al. 1998). Thus the herbage nutritive value indicates the efficiency of grazing management and the need for supplementary feeding. It is well known that high forage diets do not provide sufficient energy for milk production, especially during early lactation, and therefore energy supplements are needed. In organic farming, legume proteinrich forages are crucial for the transfer of nitrogen to the soil/plant system. Although grasses and, particularly, legumes supply N for rumen microbes, this approach is inefficient due to the large extent of N degradation in the rumen resulting in substantial losses of ammonia and N (Beever and Siddons 1986, Shingfield et al. 2001). In conventional milk production the effects of protein supplementation on animal performance in grazing animals are variable (Delaby et al. 1996, Delagarde et al. 1997, 1999, Jones-Endsley et al. 1997). Delaby et al. (1996) showed that replacement of cereals with a slowly degradable protein improved milk production to a greater extent in cows offered low compared to heavily fertilised grass swards. High-quality protein such as rapeseed feed has been shown to be a good protein supplement for conventional grass silage based diets (Huhtanen 1998). Therefore it could also be an efficient means of improving milk production in organic farming. The mineral content of pasture herbage is often not optimal for grazing animals and mineral imbalances can be detrimental to animal health and welfare (Leaver 1985, Hovi et al. 2003). This is because mineral requirements for pasture plants and grazing animals are not congruent. In addition the mineral content of pasture herbage depends on the plant species, the availability of minerals in the soil, the climatic and seasonal conditions and the stage of maturity (Underwood and Suttle 1999). The efficiency of nutrient uptake is found to change during the year, according to variation in the ambient conditions of light, temperature and soil water content, and the physiology of the plant itself (Scholefield and Fisher 2000). Soils contain varying total reserves of native nutrients. Fertilisation changes soil nutrient status. For instance, the native phosphorus reserves of Finnish soils are poorly available for plants, but the high rates of P fertilisation applied since the 1940s have significantly increased the P status of cultivated soils (Saarelainen 2003). Besides fertilisation, potassium availability depends on the prevalent soil mineralogy, but the rate at which potassium becomes available to plants is of primary significance and varies between soils and even between crop rotations (Clement and Hopper 1968). Also availability of micro nutrients, such as selenium availability, depends on soil mineralogy and is difficult to improved in organic farming systems (Eurola and Hietaniemi 2004). Complicated interactions between minerals affect the plant uptake in the soil, and selective grazing and differences in mineral absorption and utilisation affect the minerals actually utilised by the animals (Evans et al. 1986, Underwood and Suttle 1999). Mineral concentrations, forms, interactions with other minerals and even with vitamins affect mineral availability for animals and the current needs of animals affect the final utilisation of minerals. For instance, adequate P nutrition depends on the chemical forms in which P occurs in the diet, the vitamin D status of diet and animal, food intake, level of performance and the dietary Ca concentration (Underwood and Suttle 1999). Clovers are richer in Ca and Mg and many trace elements compared to 14

14 grasses (Leaver 1985) and several weeds for many minerals (Wilman and Riley 1993). Under extensive grazing systems, particularly, grasses, clovers and weeds have in clearly different mineral contents (Garcia-Ciudad et al. 1997). The botanical proportion of organic pastures is subject to changes between seasons and within-season, which may affect the mineral supply for grazing animals. 2.5 Actual problems on farms In autumn 1994, I interviewed 14 organic farms in the North Karelia region concerning their grazing management practices such as fertilisation, seed mixtures and grazing system (unpublished). Most (53 %) of the farms had converted to organic farming recently (0-5 years ago) or the conversion period was still on-going (23 %). According to the farmers, the important problems experienced with grazing were low herbage yield (54 %) and decreasing legume proportion (31 %). Red clover was the most commonly used pasture legume (67 %), followed by white clover (20 %) and alsike clover (7 %) and vetches (6 %). Regarding sward establishment, most farms (92 %) used composted manure for fertilisation, but during the following seasons only some farms (25 %) used fertilisation (urine or composted slurry). The average length of the GP was usually more than 3 days and the average interval between GPs was 3-4 weeks. From this survey study, experience from Siikasalmi Farm and several personal contacts with farmers, advisors and researchers it was evident improved grazing management of organic pastures was urgently required. A later farm study confirmed this opinion (Turkki and Viitala 1996). 3 AIMS OF THE STUDY The aims of this study were to investigate factors limiting grazing and to develop adjusted grazing management for Nordic organic dairy farming conditions. The perspectives of plants, animals and organic farming system were considered (Fig. 1). Pasture comprises a complex system with many interactions. The species composition and growing conditions affect the quantity and quality of herbage production. Plant nutrition depends on soil fertility and biological N 2 fixation (legumes), and can be improved by fertilisation. The implementation of grazing influences herbage utilisation but also future herbage growth. The nutrition of grazing cows depends on the intake and nutritive value of the herbage and can be improved by supplementary feeding. Milk is the ultimate output from the pasture. The manure from the grazing animals, uneaten herbage and dead roots, etc. are recycled to the soil. Some losses are inevitable. Applying organic production methods, herbage should grow well during the entire grazing season, animal feeding should correspond to the requirements of grazing cows and the whole system should maintain soil fertility in order to support future herbage production. Special objectives in developing grazing management for Nordic organic dairy farming were to - Characterise the quantity and quality of herbage from organic pasture in order to improve grazing management and the nutrition of the grazing animals (I, II, III, IV, V) - Find novel legume species replacing red clover to maintain an adequate legume proportion in the pasture (III, IV) 15

15 - Introduce annual legume-grasscereal mixtures for organic grazing management to balance the amount of available herbage during the grazing season and to extend the grazing season in the autumn (III) - Assess the effect of composted manure fertilisation on grazed swards (III) - Develop efficient grazing systems to improve milk yield per hectare (I, II) - Study the effect of concentrate supplementation on nutrition and animal performance (I, II, III) 4 MATERIAL AND METHODS 4.1 Site of the experiments The study was conducted at the Siikasalmi Experimental Farm of the University of Joensuu. Siikasalmi Farm is situated N, E in the commune of Liperi, province of North Karelia, within the Finnish milk production zone. Between 1992 and 1999 the University of Joensuu administered the farm, which comprised at that time 61 ha of cultivated area Implementation of grazing Weather conditions Herbage utilised Animal nutrition Supplementary feeding Seed mixture Herbage Dairy cows Milk yield Organic grazing management Plant nutrition Organic farming Manure N 2 - fixation Soil fertility Supplementary fertilisation Losses Prevalent soil type Figure 1. Elements influencing the grazing management under development for organic dairy farming. 16

16 (including 7 ha rented area). The main enterprise on the Siikasalmi farm was milk production, but cereal, beef and pigs were also produced. Conversion of the entire farm to organic production was started in 1992 and was almost complete by After converting, crop yields decreased only slightly and the milk yield improved compared to the previous conventional farming period (Granstedt 1999). The five-year crop rotation (barley/rye/rape as cover crop ley ley wheat/rye oats/oats + pea) worked well. The farm produced organic fodder for the animals (silage, pasture, hay, oats, barley, pie, rape) as well as rye and wheat for sale. According to a paired-sample t test of soil samples (54) taken from the same points in 1993 and 1998, organic farming increased the amount of available P (16.0 vs 24.3 mg l -1, P<0.001), slightly decreased the amount of available K (111 vs 97.9 mg l -1, P<0.05) and had no effect on Ca and Mg availability (unpublished). However, Siikasalmi, like many other organic farms, had unexpected difficulties with grazing after converting to organic farming Experimental design and treatments This thesis contributed data from seven experiments (Table 1). Experiment 1: Sward renovation, (Kuusela 1995, mainly unpublished) The renovation of a two-year-old clovergrass pasture by compost application and reseeding was assessed in a grazed field study in years (Kuusela 1995). At the beginning of conversion to organic farming the sward had been seeded with a clover (alsike and red clover)/ grass mixture, but in year 1994 after two years of grazing and tramping the sward vegetation had thinned out. The trial was of a randomised block design with three replicates and two treatments at two levels: 25 t ha -1 mature farmyard manure compost (CA) or no compost (NC) and 25 kg ha -1 seed sawn (SS) or no seed sawn (NS). The plot size was 20 x 10 m. Cattle manure originated from Siikasalmi farm was mixed with straw, processed one week in a drum compostory and matured approximately 8 months in a heap under permanent cover before application. The seed mixture contained 33% clover (1:1 alsike and white clover) and 67% grasses (timothy, and meadow fescue smooth-stalked meadow grass). During the application summer (1994) the area was grazed 5 times for 1-2 days by Ayrshire dairy cows, topped after the first and second grazing period (GP) and irrigated after the fourth and fifth GP. In summer 1995 the after effect of treatments on HM and botanical proportions was observed before and after the second GP. Experiment 2: Clover species for perennial grazed swards, (IV, V) A grazed field trial was established in summer 1995 in order to evaluate the suitability of white, alsike and red clover as pasture legumes in Nordic conditions. The seed mixtures evaluated were alsike clover (AM), red clover (RM), white clover (WM), white and alsike (1:1) clover (WAM) and a grass (GM) mixture. The trial was initiated using a randomised complete-block design with four replicates and five plots (17.50 x m) per replicate. Soil texture of the experimental area was defined in autumn 1993 as silty very fine sand ( mm) of medium fertility (Ca 1360, P 16, K 165, Mg 196 mg l 1 ) with an organic matter (OM) content of g kg -1 DM and ph (water) of 6.1 (Soil Analysis Service Ltd, Vuorinen and Mäkitie 1955). The complementary grasses consisted of 17

17 Table 1. Description of experiments contributing data to this thesis. Exp. No. 1 Sward renovation Compost application Reseeding Subject Treatments Measurements Publications 2 Clover species for perennial swards Sward measurements Five seed mixtures Sward measurements IV, V Kuusela 1995, mainly unpublished 3 Birdsfoot trefoil and white clover Three seed mixtures Sward measurements Unpublished 4 Grazing method, supplementary feeding Strip or paddock grazing Four supplementary feedings Sward measurements Animal measurements I, II 5 Herbage allowance, supplementary feeding Two herbage allowances Two supplementary feedings Sward measurements Animal measurements I, II 6 Compost fertilisation, legumes for annual swards 7 Legumes for annual swards, concentrate feeding regimen Compost fertilisation Four seed mixtures Two seed mixtures Two concentrate feeding regimens Sward measurements Sward measurements Animal measurements III III meadow fescue (0.50), timothy (0.43) and smooth-stalked meadow grass (0.07). The seed mixtures (25 kg ha 1, including 7.5 kg ha 1 clover in clover mixtures) were seeded with a cover crop (oats (Avena sativa), Veli, 90 kg ha 1 ). Winter-hardy red clover Bjursele, white clover Jögeva4 and alsike clover Frida cultivars were used. No fertilisers were applied. During the summer of sward establishment Ayrshire dairy cows grazed the area three times. During summers of the replicates were rotationally (21-day cycles) grazed five times per summer and years were concerned as split-plots and periods of grazing (GP1 GP5) within a year as split-split-plots. The mean stocking rates during the grazing seasons were 4.6, 3.5 and 2.9 cows ha -1 for 1996, 1997 and 1998, respectively. After GP1- GP4, replicates were topped to a mower height of 10 cm to minimise carry-over effects and to control weed growth. Experiment 3: Birdsfoot trefoil and white clover as pasture legumes ( ) A grazed field trial was established in 1997 in order to evaluate the potential of birdsfoot trefoil and white clover for use as pasture legumes. The seed mixtures were birdsfoot trefoil (BM), white clover (WM) and a grass (GM) mixture. The trial was initiated using a randomised complete-block design with three replicates and three plots (10 x 10 m) per replicate. Before the experiment, the area had been fallow for several years. The soil texture of the experimental area was silt with moderate fertility (Ca 1570, P 13, K 101, Mg 237 mg l 1 ), an organic matter (OM) content of g kg -1 dry matter (DM) and ph (water) of 6.3 (Soil Analysis Service Ltd, Vuorinen and Mäkitie 1955). The seed mixtures were sown with a cover crop (oats, 90 kg ha 1 ). The seeding rates for GM, WM, and BM were 24 kg ha 1, 24 (clover

18 grass 18 ) kg ha 1 and 29.5 (trefoil grass 18) kg ha 1, respectively. The complementary grasses consisted of meadow fescue (0.50), timothy (0.43) and smooth-stalked meadow grass (0.07). The legume cultivars were white clover Sonja and birdsfoot trefoil Cornelia. Ayrshire dairy cows grazed the area three times during the summer of establishment. During the summer of first full grazing year the area was grazed five times for 1-3 days, applying a rotation cycle of three weeks. Periods of grazing (GP1 GP5) within the grazing season were concerned as splitplots. After GP1, GP2 and GP4, the area was topped. Experiment 4: Grazing method ( ) and supplementary feeding (1997) (I, II) The effect of two rotational grazing methods, paddock (P) and strip (S) grazing, on herbage and grazing area requirement was compared. Grazing pressure was controlled achieved either by regulating the HA of the daily strips or regulating the paddock POST SH. Three pastures (1 ha) were each divided into two equal areas. The grazing method was randomly applied to areas within each pasture at the beginning of both summers. For the S grazing, cows were allocated to a fresh grazing area each day with a HA above 3 cm of 20.0 (1996) or 22.5 kg DM cow -1 (1997). For the P grazing, cows were grazed on the same paddock until a target POST SH of 10 cm was reached with an average grazing session of 6 days. The rotation cycle was in both grazing methods 21 days, but the rest period between grazing sessions became longer for daily strips than for 6-day paddocks. The total grazing time on each pasture per grazing session was equal and the S- and P-grazed cows were simultaneously transferred to the next pasture and the areas were topped after grazing. The effect of two rotational grazing methods on milk production was compared in a feeding experiment. The feeding study (1997) was conducted with 8 lactating (152 ± 51 days in milk) cows, as two 4 x 4 Latin squares, each having 21-day periods comprised of 14 days for dietary adjustment and 7 days for sample collection. The cows were divided to two balanced squares and the treatments were randomly assigned to each cow within a square. The control treatment herbage (H) consisted of pasture alone. Treatment energy (E) consisted of pasture ad libitum supplemented with 4 kg day -1 of a mixture of organic oats and barley (500/500 g kg -1 ). Treatment protein (P) consisted of pasture ad libitum supplemented with 1.25 kg day -1 of commercial rapeseed meal. Treatment energy and protein (EP) consisted of pasture ad libitum supplemented with 2.75 kg of a mixture of oats and barley (500/500 g kg -1 ) and 1.25 kg day -1 of a commercial rapeseed meal. Supplements were formulated so that the diets E and P supplied the same amount of crude protein (CP) and diets E and EP supplied equal amounts of energy. Experiment 5: Herbage allowance and supplementary feeding (1998) (I, II) The effects of low (LH) and high (HH) daily HA of 18 and 24 kg DM cow -1, on herbage and grazing area requirement was studied within a S grazing system. Three pastures were divided into two similar areas and allocated at random to the two HA treatments. The cows received fresh pasture each day. The length of the rotation cycle was adjusted to the grazing conditions and the pastures were grazed from 2 to 4 times, depending on the severity of tramping and length of the period which vegetation needed to recover. Also some additional areas were included in the grazing rotation. The cows were transferred 19

19 simultaneously to the next pasture and the grazed areas were topped. The feeding study was conducted with 8 lactating (148 ± 45 days in milk) cows as two 4 x 4 Latin squares with 21-day periods comprised of 14 days for dietary adjustment and 7 days for sample collection. The cows were divided into two balanced squares and the treatments were randomly assigned to each cow within a square. Four experimental treatments in a 2 x 2 factorial arrangement consisted of two levels of HA (18 or 24 kg DM day -1 ) and two levels of concentrate supplementation (2.5 or 5.0 kg day -1 ). The concentrate consisted of (g kg -1 ) a mixture of organic oats (450), barley (450) and commercial rapeseed meal (100). Experiment 6: Compost fertilisation and seed mixture for annual grazed swards (1999) (III) The effect of soil-deposited compost was studied with annual swards in a grazed field trial. The field trial was conducted according to a randomised completeblock design. The treatments with three replicates were fertilisation (main plot), unfertilised (U) or 25 t ha -1 farmyard manure compost (C), seed mixture (split-plot) common vetch mixture (CV), hairy vetch mixture (HV), Persian clover mixture (PC) or Persian clover white clover (PWC). The main plots measured x m with subplots of x 8.75 m. Cattle manure originated from Siikasalmi farm was mixed with straw, processed one week in a drum compostory and matured approximately 3 months in a heap under permanent cover before application. During the grazing season the experimental area was grazed 5 times by replication lactating Ayrshire cows. Periods of grazing (GP1 GP5) within the grazing season were concerned as split-splitplots. The cows were removed from each replicate when the targeted POST SH (10-12 cm) of the unfertilised areas was approached. The rotation cycle was 21 days, except 14 days between GPI and GP2. Immediately after grazing each replicate was topped. Experiment 7: Vetch- and clover-based seed mixture and concentrate regimen (1999) (III) The effect of vetch and clover based mixtures on pasture herbage was studied in Three former perennial pastures (total 3 ha) were divided into two equal areas for seeding. The seed mixtures, which consisted of a vetch- (VM) and a clover- (CM) based mixture, were allocated at random to two halves of each pasture. The herbage allowance was 21.5 kg DM (above 3 cm) per cow day -1. Small paddocks were grazed for three to four days. The size of the paddocks was determined on a HM basis to meet the HA demand. The cows in both grazing treatments were transferred simultaneously to the next pasture. After grazing, the pastures were topped. The feeding study was conducted with 8 lactating (150 ± 36 days in milk) Finnish Ayrshire cows, as two 4 x 4 Latin squares with 21-day feeding periods that consisted of a 14-day adjustment period and a 7-day recording period. The cows were divided to two balanced squares and the treatments were randomly assigned to each cow within a square. Four experimental treatments in a 2 x 2 factorial arrangement consisted of two sward mixtures (clover or vetch) and 4.0 kg day -1 of concentrate offered either 4 kg once or 2 kg twice daily. Concentrate was offered at morning milking in both feeding regimens, and at the afternoon milking in the twice-daily treatment. The concentrate consisted (g kg -1 ) of oats (375), barley (375) and rapeseed meal (250). 20